Valve for continuous boiler blowdown



Oct. 6, 1953 J. w. KAY

VALVE FOR CONTINUOUS BOILER BLOWDOWN 2 Sheets-Sheet 1 Filed Feb. 20, 1948 INVENTOR. J W (V5 71 J. M145: ATTORNEY Oct. 6, 1953 I J. w. KAYE 2,654,395

VALVE FOR commuous BOILER BLOWDOWN Filed Feb. 20, 1948 2 Sheets-Sheet 2 IN VEN TOR.

A 77'ORNEV Patented Got. 6, 1953 VALVE FOR CONTINUOUS BOILER BLOWDOWN James W. Kaye, Montclair, N. J assignor to Kaye & MacDonald, Inc., West Orange, N. J., a corporation of New Jersey Application February 20, 1948, Serial No. 9,723

3 Claims.

This invention relates to valves and more specifically to a valve assembly for continuous boiler blow-down.

In the operation of a boiler, the evaporation of the water therein tends to concentrate the feed water impurities to such an extent that if they are not removed, a hard scale forms on the inside of the boiler, the steam is dirtied, corrosion of the metal takes place and the boiler plate cracks in spots, mainly at the joints. To prevent these difficulties, it is the practice to blow-down the boiler, or, in other words to blow the impurities out of the boiler. In a continuous blow-down process, the impurities are blown out at the same rate at which they are being fed into the boiler. The present invention is directed to the improvement of valves of the type used for continuous boiler blow-down.

It is an object of this invention to provide a valve of this type in which the rate of flow can be easily and accurately regulated over a wide range.

It is another object of this invention to utilize the principle of reflash to accurately control the rate of blow-down. The term reflash is intended to be synonymous with the terms "flash steam and regenerated steam and to refer to the steam or water vapor which is formed when water at a confined pressure and at the saturation temperature for that pressure is suddenly reduced to a lower pressure. This is due to the fact that there is a difference in heat content of the water at the two different pressures and this heat difierence is used to heat or flash some of the water to steam at this lower pressure.

Another object of this invention is to provide, in a blow-down valve, improved means for protecting an orifice therein against clogging from boiler sludge concentration.

It is still another object of this invention to provide, in a blow-down valve, an improved type of valve seat, valve, restricted orifice and strainer which can be removed as a unit.

Various other objects and features of the invention will be apparent as the description proceeds.

In accordance with an illustrative embodiment of the invention, there is provided a valve assembly for continuous boiler blow-down comprising a metal casing having a filter screen mounted therein and protected from the flow of fluid from the boiler being blown-down by a bafile member and having an opening in the casing below the screen for removing sediment from the casing, a valve-controlled variable orifice, a fixed orifice, a flash tube or chamber between the two oriflees, and an outlet opening for the fluid after it passes through the fixed orifice. The restricted (fixed) orifice causes pressure to build up in the flash chamber somewhere between the outlet pressure and the inlet pressure for, when the fluid is, for example, heated water under pressure, a certain percentage of the water passing through the variable orifice will flash into steam because of the lower pressure in the flash chamber. Variation of the size of the variable orifice (other factors remaining the same), varies the pressure in the flash chamber so that for a particular valve opening, there is a definite pressure in the flash chamber and a definite flow through the fixed orifice. The pressure in the flash chamber can be measured by a gauge and the proper valve setting obtained by a correlated valve reading. A feature of the valve assembly is that by removing only two nuts, the whole assembly can be disassembled.

The invention will be more readily understood by referring to the following description, taken in connection with the accompanying drawings forming a part thereof, in which:

Fig. l is a front elevation of a valve assembly for continuous boiler blow-down constructed in accordance with the invention;

Fig. 2 is a side elevation, with portions broken away and other portions in cross-section, of the valve assembly of Fig. 1 and shows in dash-dot lines a gauge which for simplicity in the drawings is not shown in the other figures; and

Fig. 3 is a disassembled perspective View of the valve of Figs. 1 and 2.

Referring more specifically to the drawings, Figs. 1, 2 and 3 show, by way of example for purposes of illustration, a valve assembly it for continuous boiler blow down. The major parts of the valve assembly include a valve chamber body I l, a strainer i2 mounted therein behind a baffle 13, a removable and reversible valve seat i i, a valve disc 15, an upper assembly is including a valve bonnet block i! and means to be later described for controlling the position of the valve, a flash tube It part of which is surrounded by a packing gland it, a member 26 containing a restricted orifice 2i and an outlet block 22 which is attached to the casing l I. Most of these parts are shown spaced apart from one another in Fig. 3 which is an exploded view.

Passing now to a more detailed description of the valve assembly, the valve chamber body or casing l l is of heavy steel to withstand high pres sure. It is generally cylindrical in shape with a rounded bottom as shown in the drawings. It is provided with a tapped inlet 23 which is adapted to be connected to the boiler being blown-down. This inlet is opposite the bafile member 13 so that the latter serves to protect the screen l2 from the high pressure flow at the inlet. The bottom of the casing has a forged steel, tapped boss 24 which can be connected to a suitable valve (not shown) which, when opened, permits the full line pressure to blow sediment from the chamber 25 above it. The casing II has a steel head 26 which is welded or otherwise fastened to the casing or body Also fastened to the casing II (in the side thereof is the outlet block 22.

The strainer I2 is of large size and of stainless steel and is supported within the casing H (in the position shown in Fig. 2 of the drawings) from the head 26. The strainer isattached to a holder 2'! which has a shoulder 28 for supporting the removable and reversible valve seat I l, sized according to requirements. The seat has an opening 29 which is rounded to fit the valve disc i which is shaped to have a much smaller crosssection at the bottom than at the top, as shown in the drawings.

The valve disc I5 is attached to the valve stem 38 which is threaded to engage complementary threads on valve bonnet 3|. The valve disc, valve stem and bonnet are of stainless steel, the valve l5 having a Brinell hardness rating of 850 plus. The bonnet 3| is screwed into the forged steel valve block 11 which has Welded or otherwise secured thereto a pipe 32 which is connected through a T-joint 33 to the flash tube l8. The pipe 52, T-ioint 33 and flash tube I8 collectively form a flash chamber. The gauge 34 is connected through pipe 35 to the T-joint 33. The pipe 35 and the gauge 34 have been shown in Fig. 2 in dot-dash lines because they are not parts of the valve assembly it) per se. If the gauge is not used the T-joint 33 can be stopped up by a plug 36 (see Fig. 1).

The valve stem 30, for adjusting the opening between the seat I4 and the valve I 5, passes through a stuihng box in the valve bonnet 3| which is filled with stuifing 37 compressed by the stainless steel stuffing box gland 38 which is forced down by the gland nut 39, also of stainless steel, which has internal threads cooperating with external threads on the valve bonnet 3|. An index disc ll) is mounted on the end of the valve stem 35 from which disc readings corresponding to the valve setting can be taken by association with an indicator rod 4|. The valve stem and the disc 40 can be turned by a handle 42 fastened to the valve stem 30 by the valve stem lock nut 43. v

The valve bonnet block 1'! is held tightly against the valve seat It by means of two valve bonnet block studs 54 which screw into the head 25 and are capped by valve bonnet block stud nuts 65. Tightening of these nuts also forces the flash tube l8 into the member 20 having the fixed orifice 2|. The tube I8 is surrounded by a stuffing box 46, the stuffing being compressed by the easy-tight packing gland H! of stainless steel. The orifice 21 is a restricted orifice, the size of which is selected to meet the requirements of a particular valve. A packing gland clamp 47 holds the packing gland l9 tightly against the packing in the stufiing box 46. The clamp 41 is tightened by turning the screw 48 against the screw plug 49 which can be removed to clean chamber 5|) below orifice 2|. The chamber 50 connects with a tapped outlet 5|.

The operation of the valve assembly l0 will now be described. Fluid from the boiler being blowndown in introduced into the valve In through the threaded inlet 23. The fluid strikes baffle l3 and flows to the settling chamber 25. Any large particles of sediment from the boiler settle out in this chamber because of the reduction in velocity as the fluid passes through this larger chamber; The fluid then passes through the strainer screen |2 which removes dirt and solid fdreign matter, depending upon the size of the strainer holes which can be varied to suit conditions. The fluid then passes through orifice 29 which can be varied in size to produce from zero flow to maximum flow within very close limits throughout the range by positioning the valve l5 by means of the threaded valve stem 30. Fluid then passes into the chamber formed by pipe 32, T-joint 33 and tube I8 which collectively is called the flash chamber. The fluid passes from the flash tube l8 through the restricted orifice 2| which is in the disc 20 into chamber 50 and thence out through threaded port- 5|, the pressure at 5| being lower than at 23.

When the fluid is a heated liquid under pressure, such as hot water, a certain percentage of the water passing through the orifice 29 flashes into steam because of the lower pressure in the flash chamber. The restricted orifice 2| causes the pressure to build up in the flash chamber somewhere between the pressure into which the valve is exhausting at the port 5| and the inlet pressure at the port 23-. Thus, for a particular orifice disc and a constant initial pressure at the entrance 23, variation of the orifice opening 29 varies the pressure in the flash chamber so that for a particular valve opening,- there is a definite pressure in the flash chamber and a definite flow through the restricted orifice 2|. By means of the pressure gage 34, the proper valve setting can be obtained by a correlated gage reading. The micrometer index 45 located on the valve stem in cooperation with the pointer M on the valve bonnet 39 provide a means for resetting the valve [5 to any predetermined opening.

When used on continuous boiler blow-down, the blow-down concentration can be maintained to within very close limits by the proper sizing of the valve l5 orifice and the restricted orifice 2| and correlating the pressure in the flash chamber. After once setting the variable orifice 29 for a particular desired flow, determined by the blow-down concentration desired, the same flow can be obtained at another time by setting the valve to the pressure to be maintained in the flash chamber. Any change in the flow rate or in conditions shows immediately on the pressure gage. A visual check indicates whether proper new conditions exist.

Removal of valve l5, valve seat l4, strainer l2, and restricted orifice member 20 and cleaning of any parts or passages can be effected without removing the valve from the line or breaking any pipe joints. To remove the valve I5, valve seat l4, strainer l2 and restricted orifice block 20, all that is necessary is to remove the two stud nuts 45, loosen the packing gland clamp screw 48 and lift out the complete valve bonnet assembly with the valve bonnet block and reflash tubes 32 and H3 and the T-joint 33. If the packing 46 is too tight, or for any other reason the valve bonnet block W does not lift off by hand, screwing down on the valve stem 39 acts as a powerful screw jack and the valve bonnet block I"! rises with ease. The valve l5, normally held tightly against the valve seat l4 and strainer holder 27 by valve bonnet block I! which is held down by the two stud nuts 45, is now easily lifted up. The valve seat 14 and strainer holder 27 with the strainer l2 attached can then be lifted out. To remove the restricted orifice member 20, the packing gland I9 is lifted, the packing 46 removed and the restricted orifice member 2 lifted out with a suitable hooked tool; or, by removing threaded plug 49, a rod can be used to push out the restricted orifice member 20 and, at the same time, push the packing 46 ahead of it. To remove the valve disc i5, the valve stem 30 is screwed down until the valve disc I5 is completely below the valve bonnet block I! and the disc is then slipped from the valve stem 30. From the foregoing, it is readily seen how quickly and easily the valve seat l4, strainer I2, valve disc I5 and restricted orifice member 20 can be removed for replacement, inspection or cleaning without removing the valve assembly l from the line.

By referring to the drawings, it is readily evident that there are no inaccessible ports, passages or crevices to become clogged by foreign matter. The strainer l2 prevents any large particles of solids which might clog either of the orifices from ever coming into contact with them. If, under small fiow conditions, enough dirt accumulates in the variable orifice 29 to clog it, screwing down on the valve stem 30 forces the elongated tip of the valve disc IE to punch through and clear the orifice. To clean orifice 2i and the fiash chamber, all that is necessary is to remove packing gland clamp 47, unscrew plug 49, and force a rod up to and through orifice 2| via the tapped port for plug 49 and foreign matter present can then be loosened and then blown out by opening valve I The tapped boss 24 is, as mentioned above, provided for the connection of a suitable valve which, when opened, allows the full line pressure to blow the sediment from chamber 25.

Various changes can be made in the embodiments described above without departing from the spirit of the invention, the scope of which is indicated by the claims.

What is claimed is:

1. A valve comprising a casing having inlet and outlet openings, a valve seat adjacent said outlet, a valve bonnet block adjacent said valve seat, a valve bonnet screwed in said block and having a central opening therein a portion of which has internal screw threads, a valve stem passing through said central opening and having external screw threads thereon cooperating with the internal threads of said valve bonnet, a valve disc fastened to the end of said stem and positioned to move with respect to said seat to vary the opening therein when said valve stem is turned, said valve bonnet block having an outlet port, and said casing having an outlet block at the side thereof provided with a chamber therein and an outlet port therefor, a member having a calibrated orifice therein positioned on a ledge in said outlet block above said chamber, conduit means forming a flash chamber and connecting the outlet port of said valve bonnet and said orificed member, a packing box surrounding a portion of said conduit means which is within said outlet block, a packing gland for holding the packing in said box in position, and easily removable means for connecting said valve bonnet block to the top of said casing and thereby holding said valve seat in position.

2. A valve comprising a casing having inlet and outlet openings, a valve seat supported by said casing above said outlet opening, a valve block positioned adjacent said valve seat and including, in an opening therein, a movable valve disc to Vary the orifice opening in said seat, means forming an outlet chamber attached to saidcasing, a removable member having an orifice of fixed size supported within said outlet chamber, conduit means forming a flash chamber connected to said opening in the valve block and having an outlet end terminating adjacent said orifice of fixed size, a packing box surrounding a portion of said conduit means which is within said outlet block, a packing gland for holding the packing in said box in position, and easily removable means for connecting said valve block to the top of said casing and thereby holding the valve seat in position.

3. A valve comprising a casing having inlet and outlet openings, a valve seat supported by said casing above said outlet opening, a valve block positioned adjacent said valve seat and including, in an opening therein, a movable valve disc to vary the orifice opening in said seat, means forming an outlet chamber attached to said casing, a removable member having an orifice of fixed size supported within said outlet chamber, conduit means forming a flash chamber connected to said opening in the valve block and having an outlet end terminating adjacent said orifice of fixed size, a packing box surrounding a portion of said conduit means which is within said outlet block, a packing gland for holding the packing in said box in position, and means including a pair of studs for attaching said valve block to said casing to hold said valve seat in fixed position and also to position said flash chamber outlet end in said outlet chamber adjacent said orifice of fixed size.

JAMES W. KAYE.

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